From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21EF1C33CB1 for ; Thu, 16 Jan 2020 14:01:30 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 02D852075B for ; Thu, 16 Jan 2020 14:01:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 02D852075B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=chris-wilson.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B47B06ED1F; Thu, 16 Jan 2020 14:01:26 +0000 (UTC) Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id E7C6D6ED1E; Thu, 16 Jan 2020 14:01:24 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from localhost (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP (TLS) id 19901846-1500050 for multiple; Thu, 16 Jan 2020 14:01:21 +0000 MIME-Version: 1.0 To: Daniel Vetter , David Laight From: Chris Wilson In-Reply-To: <90de9ae911dc481f9c2c62e196b2bacf@AcuMS.aculab.com> References: <20200115205245.2772800-1-chris@chris-wilson.co.uk> <20200116065242.GC8400@dvetter-linux.ger.corp.intel.com> <157916041994.14122.8524532515240369595@skylake-alporthouse-com> <8f6b9daa2af342a79137064203255242@AcuMS.aculab.com> <157917771007.2795.953028640868055754@skylake-alporthouse-com> <90de9ae911dc481f9c2c62e196b2bacf@AcuMS.aculab.com> Message-ID: <157918327903.2795.11869462469060447820@skylake-alporthouse-com> User-Agent: alot/0.6 Date: Thu, 16 Jan 2020 14:01:19 +0000 Subject: Re: [Intel-gfx] [PATCH] drm: Inject a cond_resched() into long drm_clflush_sg() X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "intel-gfx@lists.freedesktop.org" , "dri-devel@lists.freedesktop.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Quoting David Laight (2020-01-16 13:58:44) > From: Chris Wilson > > Sent: 16 January 2020 12:29 > > > > Quoting David Laight (2020-01-16 12:26:45) > > > However there is a call from __i915_gem_objet_set_pages() that > > > is preceded by a lockdep_assert_held() check - so mustn't sleep. > > > > That is a mutex; it's allowed to sleep. The might_sleep() here should > > help assuage your fears. > > Gah. Having a mutex called mm.lock isn't entirely obvious when quickly > reading code. > > From what I was reading earlier it seems that clflush() (and cflushopt) > are fast (well not stupidly slow) for buffers under 4k. > I suspect then can do a 'mark pending', but for larger buffers have to > wait for earlier requests to complete (although the graph carries on > increasing to the 16k RH margin. > > If may well be that adding a cond_resched() after every 4k page > will have ~0 performance impact because the first few clflush > will be a bit faster (less slow). > > I'll do some measurements later this afternoon. > > FWIW does this code need to actually invalidate the cache lines? > Or is it just forcing a writeback? It is used for both. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx